1. Field of the Invention
The present invention relates to a sheet handling apparatus for feeding a sheet to a predetermined position.
2. Related Background art
In an image forming apparatus such as a copying machine, a sheet handling apparatus or a document feeder is often employed as an attachment for feeding original documents to a predetermined position such as an exposure position.
Such document feeder, often made available as an optional attachment for a copying machine, is therefore subjected to various limitations for example in size, weight and cost, and is required to satisfy various requirements such as a short document exchange time, an automatic document size detection and satisfactory document transportation.
In such conventional document feeder, the automatic document size detection has been achieved by measuring the time from the detection of the front end of a document to the detection of the rear end thereof by a sensor provided at an entrance position for the document. However, such detecting method has not allowed precise size detection due for example to a slipping of rollers.
Also in case such document feeder is employed for copying, satisfactory feeding and discharge of documents cannot be achieved, if another document is left on the platen by mistake, due to the collision of such left document and a newly fed document.